Anatomical relationships among the median nerve thenar branch, superficial palmar arch, and transverse carpal ligament

The Reliability of Kaplan's Cardinal Line as a Potential Surface Marker for the Superficial Palmar Arch During Carpal Tunnel Release: An Anatomical Study With Surgical Perspective

Purpose Kaplan's cardinal line (KCL) provides a more accurate reference point to the superficial palmar arch (SPA). The aim was to determine the KCL-SPA distances and their relationship with the other defined superficial landmarks, such as distal wrist crease (DWC) or distal portion of the transverse carpal ligament (TCL) or DWC-TCL distance. The objective was to determine the distal limit of the incision made during carpal tunnel release (CTR). Methods Sixty hands were dissected after KCL was drawn on each hand using standard methods. The distance from KCL to the SPA was measured along the radial and ulnar borders of the ring finger and recorded as radial and ulnar KCL-SPA distance, respectively. The distance between the DWC and the distal portion of the TCL was also measured (DWC-TCL). Correlation analysis was done between the DWC-TCL and KCL-SPA distance. The ratios between the radial and ulnar KCL-SPA distance and DWC-TCL distance were calculated and mentioned as radial and ulnar Kaplan cardinal index, respectively. Results KCL-SPA distance was 6.8±3.7 mm along the radial border and 6.6±3.6 mm along the ulnar border of the ring finger. The DWC-TCL distance was 29.4±1.2 mm. The means of radial and ulnar Kaplan cardinal indices were 0.23 and 0.22, respectively. A significant correlation was found between the DWC-TCL distance and the KCL-SPA distances. Conclusion Clinically, KCL can be appraised as a predictable surface landmark in limiting the distal-most extent of the incision during CTR and protecting SPA from transection. The SPA was found to lie at a variable distance from the KCL, and the minimum distance was found to be 3.3 mm. This should be considered as the maximum permissible extension of CTR incision beyond KCL.

Carpal tunnel mechanics and its relevance to carpal tunnel syndrome

The carpal tunnel is an elaborate biomechanical structure whose pathomechanics plays an essential role in the development of carpal tunnel syndrome. The purpose of this article is to review the movement related biomechanics of the carpal tunnel together with its anatomical and morphological features, and to describe the pathomechanics and pathophysiology associated with carpal tunnel syndrome. Topics of discussion include biomechanics of the median nerve, flexor tendons, subsynovial tissue, transverse carpal ligament, carpal tunnel pressure, and morphological properties, as well as mechanisms for biomechanical improvement and physiological restoration. It is our hope that the biomechanical knowledge of the carpal tunnel will improve the understanding and management of carpal tunnel syndrome.

Prospective Comparative Analysis Study of Minimally Invasive Surgical Decompressions versus Traditional Surgical Decompression of Carpal Tunnel Syndrome

Objective: Carpal tunnel syndrome (CTS) occurs when there is compression on the median nerve within the carpal tunnel in the wrist joint. It commonly affects those who make frequent, repetitive hand movements, with women being more affected than men. The present study was aimed at comparing minimally invasive and classical surgical decompression techniques for carpal tunnel syndrome. Materials and Methods: One hundred and four patients with CTS who were scheduled for carpal tunnel decompression were chosen at random. The patients were divided into two groups. Group A had standard classical long incision decompression, whereas Group B had minimally invasive decompression. The patients were evaluated with the Boston Functional Score Scale. Between the two groups, a comparison of visit reports was made at 3, 6, and 12 months after surgery. Results: There was no significant difference in patient age (Group A was 38 years old and Group B was 36 years old) and availability of bilateral CTS status (A was 34 and B was 31). The female-male ratios in groups A and B were 3.6 to 0.2 and 3.1 to 0.3, respectively, with a p-value of p<0.05 indicating significant difference. Comparing both groups, the minimally invasive decompression technique showed a high rate of functional hand grip and a low rate of complications including early wound healing, rapid resumption of palmar strength grip, and rapid return to daily activities. Conclusion: The findings indicate that patients who underwent the minimally invasive surgical decompression one-stitch technique showed significant improvement over the traditional method.

Thenar and Hypothenar Muscle Coverage on the Transverse Carpal Ligament

Background  The purpose of the study was to examine the coverage of thenar and hypothenar muscles on the transverse carpal ligament (TCL) in the radioulnar direction through in vivo ultrasound imaging of the carpal tunnel. We hypothesized that the TCL distance covered by the thenar muscle would be greater than that by the hypothenar muscle, and that total muscle coverage on the TCL would be greater than the TCL-alone region. Methods  Ultrasound videos of human wrist were collected on 20 healthy subjects. Automated algorithms were used to extract the distal cross-sectional image of the trapezium-hamate level. Manual tracing of the anatomical features was conducted. Results  Thenar muscles covered a significantly larger distance (11.9 ± 1.8 mm) as compared with hypothenar muscles (1.7 ± 0.8 mm) ( p  < 0.001). The TCL covered by thenar and hypothenar muscles was greater than the TCL-alone length ( p  < 0.001). The thenar and hypothenar muscle coverage on the TCL, as normalized to the total TCL length, was 61.0 ± 7.5%. Conclusions  More than 50% of the TCL at the distal carpal tunnel is covered by thenar and hypothenar muscles. Knowledge of muscular attachments to the TCL improves our understanding of carpal tunnel syndrome etiology and can guide carpal tunnel release surgery.

Effectiveness and safety of surgical treatment of carpal tunnel syndrome via a mini-transverse incision and a bush hook versus a mid-palmar small longitudinal incision

Background

Minimally invasive surgery for carpal tunnel syndrome has been consistently the mainstay of treatment. In this study, we developed a novel bush hook via a mini-transverse incision at proximal wrist crease to surgically treat carpal tunnel syndrome and our aim was to compare the results with those of mid-palmar small longitudinal incision in carpal tunnel release.

Methods

This is a retrospective study on patients who received a mini-transverse incision and a novel bush hook or a mid-palmar small longitudinal incision for treatment of carpal tunnel syndrome. The decision to receive either technique was made mainly based on patients' choice. The clinical results were evaluated at 1 week, 1 month, 3 and 6 months postoperatively and compared.

Results

In total, 58 patients in mini-transverse incision group and 74 in mid-palmar longitudinal incision group were include. The follow-up period was 6.8 ± 1.6 months. The mini-transverse incision group had a significantly smaller incision (4.3 ± 0.4 mm vs. 26.2 ± 1.6 mm), shorter surgical time (7.8 ± 2.6 min vs. 19.7 ± 2.8 min), but not for hospital stay (3.2 ± 1.9 vs. 3.6 ± 2.2 days). Both groups showed significant improvement from baseline level at any time points postoperatively (all P < 0.001). At 1 month and 3 months, the mini-transverse incision group showed a significantly better improvement of VAS, SSS and FSS score (P < 0.05). At 6 months, the differences were no longer significant (P > 0.05). In addition, the mini-transverse incision group showed a significantly reduced time to return to the work and activities, tendency to higher rate of excellence and good outcomes and fewer complications.

Conclusions

This novel technique via a mini-transverse incision and bush hook showed better clinical effectiveness and safety, and can be considered as an alternative for wrist tunnel release after the results are validated by higher-level evidence studies.

Evidence level: III.

An Anatomical Study of the Palmaris Brevis, Transverse Carpal Ligament, and the Recurrent Motor Branch of the Median Nerve

Background: The anatomical structures in relation to the carpal tunnel release are the palmaris brevis muscle (PBM), transverse carpal ligament (TCL), and the recurrent motor branch of the median nerve (RMBMN). Our aim is to describe the gross morphology in the Korean population of the PBM, TCL, and RMBMN specifically looking for anomalies, and to determine the muscles encountered during a standard carpal tunnel release. Material and Methods: A total of 30 cadaveric hands were dissected. A longitudinal line drawn from the third web space to the midpoint of the distal wrist crease served as the reference line (RL). The PBM and TCL were classified according to its shape and location. The length, width, and thickness of the TCL were measured. The ratio of the lengths of PBM and TCL to RL was calculated. The course of the RMBMN was dissected specifically looking for anomalies. We also looked at the muscle fibers encountered during a standard carpal tunnel release to identify the muscle. Results: PBM was classified into three different types based on the shape. The average thickness of the PBM and TCL were 0.89 ± 0.16 mm and 1.43 ± 0.40 mm, respectively. The distal border of the TCL was thicker than the proximal border. The average ratio of the length of the PBM to the RL was 25.65 ± 8.62% and TCL to the RL was 24.00 ± 3.37%. The distribution of the RMBMN was classified into three different types. A few accessory branches of the RMBMN were also noted. And 36 muscle fibers were noted within the TCL in line with the RL. Conclusion: We clarified findings and added quantitative information about the anatomical structures surrounding carpal tunnel. A thorough knowledge of the anatomy and anomalies around the carpal tunnel is helpful for surgeons to ensure optimal surgical results.

Comparison of the Therapeutic Effect of the Mini-Open Incision and Conventional Open Neurolysis of the Median Nerve for Carpal Tunnel Syndrome

OBJECTIVE

The aim of this study was to compare the therapeutic effects of the mini-open incision and conventional open surgery for carpal tunnel syndrome (CTS).

METHODS

The clinical data of 52 patients with CTS treated at the First Affiliated Hospital of the University of Science and Technology of China from October 2020 to February 2022 were retrospectively analyzed. The patients were divided into the conventional open surgery group (28 cases) and the mini-open incision group (24 cases) according to different surgical incisions applied. The incision length, operation time, time until postoperative return to work, and complications were observed in the two groups. The Visual Analog Scale (VAS) for pain at one day, one month, and three months after surgery and the Boston Carpal Tunnel Questionnaire scores before, at one month, and at three months after surgery were compared between the two groups.

RESULTS

The incision length, operation time, and time until return to work in the mini-open incision group were all shorter than those in the conventional open surgery group (2.58 ± 0.35 vs. 7.32 ± 0.61 cm, 18.67 ± 2.62 vs. 29.46 ± 3.42 min, and 5.33 ± 1.40 vs. 13.86 ± 2.70 d, respectively), and differences were statistically significant (P < 0.05 in all). The VAS scores in the mini-open incision group were lower than those in the conventional open surgery group at one day and one month after surgery, while the difference in the VAS scores at three months after surgery was not statistically significant between the two groups. There was no statistically significant difference in neurological recovery between the two groups at postoperative follow-ups (P > 0.05). The incidences of postoperative scar hyperplasia and scar pain were higher in the conventional open surgery group than those in the mini-open incision group, and differences were statistically significant (P < 0.05 in both).

CONCLUSION

Mini-open incision surgery for CTS was a safe and reliable procedure with a precise therapeutic effect, minimal surgical trauma, and high postoperative comfort for patients and could achieve enhanced recovery. Trial Registration. This trial is registered with ChiCTR2200064631.

Ultrasonography of the Peripheral Nerves of the Forearm, Wrist and Hand: Definition of Landmarks, Anatomical Correlation and Clinical Implications

BACKGROUND

 Peripheral nerve pathologies of the upper extremity are increasingly assessed by high-resolution ultrasonography (HRUS), yet rapid identification of nerve segments can be difficult due to small nerve diameters and complex regional anatomy. We propose a landmark-based approach to speed up and facilitate evaluation and intervention in this region.

METHOD

 Relevant landmarks and section planes for eleven nerve segments of the forearm, wrist and hand were defined by ultrasonography in cadaver arms before cryosection and topographical neurovascular preparation. Information on all nerve segments and a pictorial guide including anatomical cross-sections, topographical preparations and HRUS images are provided. The identification rates of these nerve segments were then assessed in 20 healthy volunteers.

RESULTS AND CONCLUSION

 Sonographic landmarks and guidelines for the rapid identification and assessment of nerves of the forearm, wrist and hand are presented in pictorial and tabular form, including discussion of normal variants. Utilizing this overview should facilitate training, diagnostic examinations and intervention for nerves of the upper extremity.

KEY POINTS

  · High-resolution ultrasound enables assessment of peripheral nerves of the forearm, wrist and hand.. · A landmark-based approach can facilitate and speed up nerve evaluation in these regions.. · High detection rates could be reproduced using the proposed landmark-based approach..

CITATION FORMAT

· Gruber L, Loizides A, Peer S et al. Ultrasonography of the Peripheral Nerves of the Forearm, Wrist and Hand: Definition of Landmarks, Anatomical Correlation and Clinical Implications. Fortschr Röntgenstr 2020; 192: 1060 - 1072.

Normal Palmar Anatomy and Variations That Impact Median Nerve Decompression

Annually, carpal tunnel release is one of the most commonly executed orthopaedic procedures. Despite the frequency of the procedure, complications may occur as a result of anatomic variations. Understanding both normal and variant anatomy, including anomalies in neural, vascular, tendinous, and muscular structures about the carpal tunnel, is fundamental to achieving both safe and efficacious surgery. Reviewing and aggregating this information reveals certain principles that may lead to the safest possible surgical approach. Although it is likely that no true internervous plane or so-called safe zone exists during the approach for carpal tunnel release, the long-ring web space axis does appear to pose the lowest risk to important structures.

High-resolution ultrasound visualization of the recurrent motor branch of the median nerve: normal and first pathological findings

Purpose

To evaluate in a prospective study the possibility of visualization and diagnostic assessment of the recurrent motor branch (RMB) of the median nerve with high-resolution ultrasound (HRUS).

Materials and methods

HRUS with high-frequency probes (18–22 MhZ) was used to locate the RMB in eight fresh cadaveric hands. To verify correct identification, ink-marking and consecutive dissection were performed. Measurement of the RMB maximum transverse-diameter, an evaluation of the origin from the median nerve and its course in relation to the transverse carpal ligament, was performed in both hands of ten healthy volunteers (n = 20). Cases referred for HRUS examinations for suspected RMB lesions were also assessed.

Results

The RMB was clearly visible in all anatomical specimens and all volunteers. Dissection confirmed HRUS findings in all anatomical specimens. Mean RMB diameter in volunteers was 0.7 mm ± 0.1 (range, 0.6–1). The RMB originated from the radial aspect in 11 (55%), central aspect in eight (40%) and ulnar aspect in one (5%) hand. Nineteen (95%) extraligamentous courses and one (5%) subligamentous course were detected. Three patients with visible RMB abnormalities on HRUS were identified.

Conclusion

HRUS is able to reliably visualize the RMB, its variations and pathologies.

Key Points

• Ultrasound allows visualization of the recurrent motor branch of the median nerve.

• Ultrasound may help clinicians to assess patients with recurrent motor branch pathologies.

• Patient management may become more appropriate and targeted therapy could be improved.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-016-4671-1) contains supplementary material, which is available to authorized users.

Sonographic Visualization of Thenar Motor Branch of the Median Nerve: A Cadaveric Validation Study

BACKGROUND

The thenar motor branch (TMB) of the median nerve may be affected in carpal tunnel syndrome and can be injured during carpal tunnel surgery. Although ultrasound has been used to identify small nerves throughout the body, the sonographic evaluation of the TMB has not been investigated formally.

OBJECTIVE

To document the ability of ultrasound to visualize the TMB of the median nerve in an unembalmed cadaveric model.

DESIGN

Prospective laboratory investigation.

SETTING

Procedural skills laboratory at a tertiary medical center.

METHODS

On the basis of anatomical descriptions, dissection and clinical experience, a technique was developed to sonographically identify the presumed TMB of the median nerve at the distal carpal tunnel. A single, experienced examiner then identified the presumed TMB in 10 unembalmed, cadaveric upper limb specimens (4 right, 6 left) obtained from 9 donors (4 male, 5 female) ages 76-85 years with body mass indices of 18.2-29.5 kg/m² with both 12-3 MHZ and 16-7 MHz linear array transducers. The same examiner then injected 0.2-0.3 mL of diluted colored latex into and around the presumed TMB using direct ultrasound guidance. At a minimum of 24 hours postinjection, specimens were dissected under loupe magnification to determine the location of the latex injectate.

MAIN OUTCOME MEASURE

The location of latex injectate relative to the anatomically identified TMB.

RESULTS

A vertical, linear, hypoechogenic region was sonographically identified arising from the median nerve at the distal carpal tunnel in all 10 specimens and was hypothesized to represent the vertical segment of the TMB. Both transducers allowed identification of the TMB, although localization was subjectively facilitated by the higher frequency transducer. All 10 sonographically guided injections placed latex into and around the TMB of the median nerve, confirming that ultrasound had accurately identified the TMB.

CONCLUSIONS

Sonographic evaluation of the TMB of the median nerve is technically feasible and should be considered when clinically indicated. Further research and clinical experience is necessary to define the role of sonographic TMB imaging in the evaluation and management of patients with carpal tunnel syndrome.

LEVEL OF EVIDENCE

IV.

The double tunnels technique: an alternative minimally invasive approach for carpal tunnel syndrome

OBJECT

The purpose of this study was to assess the effectiveness and safety of an alternative minimally invasive technique for the treatment of carpal tunnel syndrome (CTS).

METHODS

This was designed as a prospective, randomized, open-label, blinded end point evaluation (PROBE) study. The active comparison was double tunnels technique (DTT) (Group A, 110 patients) versus standard open decompression of the median nerve (control [Group B], 110 patients). Patient recruitment started in January 2011. The primary outcomes were the functional Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ) scores and visual analog scale (VAS) scores for pain (pVAS) at Weeks 2 and 4, and at Months 3, 6, and 12. The secondary outcome was the aesthetics (aVAS) score at Weeks 2 and 4, and at Months 3, 6, and 12.

RESULTS

The Student t-test and ANOVA were used, and the results were considered statistically significant if the p value was ≤ 0.05 for continuous variables. The DTT is a tissue-sparing approach that allows the surgeon to limit the length of the incision (0.6 ± 0.05 cm) and to respect the palmar fascia and the subcutaneous tissue. Recovery from wrist pain, night pain, numbness, stiffness, and weakness was achieved more effectively and quickly compared with the standard approach. Better BCTSQ, pVAS, and aVAS scores were observed in Group A.

CONCLUSIONS

The DTT is a safe and effective approach for the treatment of CTS. This technique entails faster recovery times, better aesthetic outcomes, and lower risks of complications.

The Prevalence of Anatomical Variations of the Median Nerve in the Carpal Tunnel: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVE

The course and branches of the median nerve (MN) in the wrist vary widely among the population. Due to significant differences in the reported prevalence of such variations, extensive knowledge on the anatomy of the MN is essential to avoid iatrogenic nerve injury. Our aim was to determine the prevalence rates of anatomical variations of the MN in the carpal tunnel and the most common course patterns and variations in its thenar motor branch (TMB).

STUDY DESIGN

A systematic search of all major databases was performed to identify articles that studied the prevalence of MN variations in the carpal tunnel and the TMB. No date or language restrictions were set. Extracted data was classified according to Lanz's classification system: variations in the course of the single TMB--extraligamentous, subligamentous, and transligamentous (type 1); accessory branches of the MN at the distal carpal tunnel (type 2); high division of the MN (type 3); and the MN and its accessory branches proximal to the carpal tunnel (type 4). Pooled prevalence rates were calculated using MetaXL 2.0.

RESULTS

Thirty-one studies (n = 3918 hands) were included in the meta-analysis. The pooled prevalence rates of the extraligamentous, subligamentous, and transligamentous courses were 75.2% (95%CI:55.4%-84.7%), 13.5% (95%CI:3.6%-25.7%), and 11.3% (95%CI:2.4%-23.0%), respectively. The prevalence of Lanz group 2, 3, and 4 were 4.6% (95%CI:1.6%-9.1%), 2.6% (95%CI:0.1%-2.8%), and 2.3% (95%CI:0.3%-5.6%), respectively. Ulnar side of branching of the TMB was found in 2.1% (95%CI:0.9%-3.6%) of hands. The prevalence of hypertrophic thenar muscles over the transverse carpal ligament was 18.2% (95%CI:6.8%-33.0%). A transligamentous course of the TMB was more commonly found in hands with hypertrophic thenar muscles (23.4%, 95%CI:5.0%-43.4%) compared to those without hypertrophic musculature (1.7%, 95%CI:0%-100%). In four studies (n = 423 hands), identical bilateral course of the TMB was found in 72.3% (95%CI:58.4%-84.4%) of patients.

CONCLUSIONS

Anatomical variations in the course of the TMB and the MN in the carpal tunnel are common in the population. Thus, we recommend an ulnar side approach to carpal tunnel release, with a careful layer by layer dissection, to avoid iatrogenic damage to the TMB.

Colour difference of subcutaneous fat and palmar fat pad in open carpal tunnel release

BACKGROUND

Carpal tunnel syndrome is the most common compression neuropathy of the extremity. The most frequent occurring post-operative complication of open carpal tunnel release is the incomplete release of the transverse carpal ligament. A constant pad of palmar fat pad has been found to provide a reliable indicator of the distal extent of the surgical decompression of the transverse carpal ligament. We investigated the colour difference between subcutaneous fat and palmar fat pad.

METHODS

This is a prospective case series of 15 patients undergoing open carpal tunnel release. Digital images of the patients' subcutaneous and palmar fat were taken. The colour of each type of fat was described in a device independent, objective manner using the CIELab colour space. The colour difference was measured using ΔE, the Euclidean distance between the CIELab coordinates of the colours. Wilcoxon signed-rank test was used to compare colour character differences between subcutaneous and palmar fat. The colour difference, ΔE, was assessed and reported with 95% confidence intervals (CI).

RESULTS

There is a visually detectable colour difference between subcutaneous and palmar fat. The minimum ΔE was 4.45. The mean ΔE was 13.03 (95% CI 9.79-16.27). The palmar fat pad is more yellow than the subcutaneous fat (P = 0.002).

CONCLUSIONS

Our findings can assist in the identification of the palmar fat pad to ensure safer and a complete release of the transverse carpal ligament in carpal tunnel release.

A handy review of carpal tunnel syndrome: From anatomy to diagnosis and treatment

Carpal tunnel syndrome (CTS) is the most commonly diagnosed disabling condition of the upper extremities. It is the most commonly known and prevalent type of peripheral entrapment neuropathy that accounts for about 90% of all entrapment neuropathies. This review aims to provide an outline of CTS by considering anatomy, pathophysiology, clinical manifestation, diagnostic modalities and management of this common condition, with an emphasis on the diagnostic imaging evaluation.

Anatomical landmarks for safer carpal tunnel decompression: an experimental cadaveric study

BACKGROUND

Carpal tunnel syndrome is a common presentation to surgical outpatient clinics. Treatment of carpal tunnel syndrome involves surgical division of the flexor retinaculum. Palmar and recurrent branches of the median nerve as well as the superficial palmar arch are at risk of damage.

METHODOLOGY

Thirteen cadavers of Sri Lankan nationality were selected. Cadavers with deformed or damaged hands were excluded. All selected cadavers were preserved with the conventional arterial method using formalin as the main preservative. Both hands of the cadavers were placed in the anatomical position and dissected carefully. We took pre- determined measurements using a vernier caliper. We hypothesized that the structures at risk during carpal tunnel decompression such as recurrent branch of the median nerve and superficial palmar arch can be protected if simple anatomical landmarks are identified. We also hypothesized that an avascular area exists in the flexor retinaculum, identification of which facilitates safe dissection with minimal intra operative bleeding. Therefore we attempted to characterize the anatomical extent of such an avascular area as well as anatomical landmarks for a safer carpal tunnel decompression.Ethical clearance was obtained for the study.

RESULTS

In a majority of specimens the recurrent branch was a single trunk (n =20, 76.9%). Similarly 84.6% (n = 22) were extra ligamentous in location. Mean distance from the distal border of the TCL to the recurrent branch was 7.75 mm. Mean distance from the distal border of TCL to the superficial palmar arch was 11.48 mm. Mean length of the flexor retinaculum, as measured along the incision, was 27.00 mm. Mean proximal and distal width of the avascular area on TCL was 11.10 mm and 7.09 mm respectively.

CONCLUSION

We recommend incision along the radial border of the extended ring finger for carpal tunnel decompression. Extending the incision more than 8.16 mm proximally and 7.75 mm distally from the corresponding borders of the TCL should be avoided. Incision should be kept to a mean length of 27.0 mm, which corresponds to the length of TCL along the above axis. We also propose an avascular area along the TCL, identification of which minimizes blood loss.

Thenar motor neuropathy electrophysiological study of 28 cases

PURPOSE

To report an electrophysiological study on thenar motor neuropathy of the median nerve.

METHODS

Twenty-eight consecutive patients (mean age, 48.8 years; 17 men) with dominant hand thenar muscle weakness without sensory symptoms were enrolled in this study. Electromyography of hand and forearm muscles and neurography of median, ulnar, radial, and palmar nerves, including distal motor latency recording from the second interosseous-lumbrical muscles, were performed.

RESULTS

Complete denervation of the abductor pollicis brevis muscle was observed in one case and delayed median abductor pollicis brevis-distal motor latency was observed in the others. Other neurographic findings were normal.

CONCLUSIONS

Thenar motor neuropathy may have different pathogeneses. It may be considered a variant of carpal tunnel syndrome involving the motor branch only or more likely due to chronic direct compression of the branch, because it preferentially affects males, dominant hand, and persons doing manual work. In both cases, anatomic origin and variations in the course of the branch may favor thenar motor neuropathy.

The Clinical Application of Kaplan's Cardinal Line as a Surface Marker for the Superficial Palmar Arch

We feel the original description of Kaplan's cardinal line provides a more accurate reference point to the superficial palmar arterial arch. We sought to anatomically correlate the relationship of Kaplan's cardinal line to the superficial palmar arch. Sixty hands (30 cadavers) were dissected after Kaplan's original description was drawn on each hand. Measurements we made from Kaplan's cardinal line to the superficial palmar arch at both the radial and ulnar borders of the ring finger. The superficial palmar arterial arch was an average of 10.4 and 11.8 mm from the radial and ulnar borders of the ring finger with standard deviations of roughly 4 mm for each measurement. Clinically, Kaplan's cardinal line is a more predictable landmark for the superficial palmar arch. In referencing this landmark as the distal most extent of an open or endoscopic carpal tunnel release, the superficial palmar arch should be free of transection.

Carpal tunnel syndrome: treatment with small transverse incision

OBJECTIVE: To evaluate the application of a limited transverse incision technique to treat the carpal tunnel syndrome, with concern to its safety and efficacy in the opening of the flexor retinaculum (FR). METHOD: A prospective analysis of thirty FR release procedures performed on twenty-eight patients subjected to the proposed incision technique. Safety and total opening of the FR were evaluated through a questionnaire and an endoscopic inspection respectively. RESULTS: No major complications were observed. Two cases presented small local hematoma. One patient presented with transient neuropraxia of digital branch. In two of the first five cases, incomplete FR opening was identified during endoscopic revision with need of complementary opening. All patients reported relief of paresthesias and nocturnal pain symptoms. CONCLUSION: The technique was safely performed on the prospection group, no major complications were detected and the opening of FR was observed in the majority of the patients.

Mini open carpal tunnel release using Knifelight: evaluation of the safety and effectiveness of using a single wrist incision (cadaveric study)

This cadaveric study evaluates the margin of safety and technical efficacy of mini open carpal tunnel release performed using Knifelight (Stryker Instruments) through a transverse 1 cm wrist incision. A single investigator released 32 wrists in 17 cadavers. The wrists were then explored to assess the completeness of release and damage to vital structures including the superficial palmar arch, palmar cutaneous branch and recurrent branch of the median nerve. All the releases were complete and no injury to the median nerve and other structures were observed. The mean distance of the recurrent motor branch to the ligamentous divisions was 5.7 +/- 2.4 mm, superficial palmar arch was 8.7 +/- 3.1 mm and palmar cutaneous branch to the ligamentous division was 7.2 +/- 2.4 mm. The mean length of the transverse carpal ligament was 29.3 +/- 3.7 mm. Guyon's canal was preserved in all cases.

Definition of a safe-zone in open carpal tunnel surgery: a cadaver study

Carpal tunnel decompression is one of the most common surgical procedures in hand surgery. Cutaneous innervation of the palm by median and ulnar nerves was evaluated to find a suitable incision preserving cutaneous nerves. A morphometric study was designed to define the safe-zone for mini-open carpal tunnel release. Sixteen fresh-frozen (8 right, 8 left) and 14 formalin-fixed (8 right, 6 left) cadaveric hands were dissected. Anatomy of the palmar cutaneous branch of the median and the ulnar nerve, motor branch of the median nerve, superficial palmar arch were evaluated relative to the surgical incision. We also identified the motor branch of the median nerve. Detailed measurements of the whole palmar region are reported in this study. The motor branch of the median nerve was extraligamentous as 60%, subligamentous as 34%, transligamentous as 6%. The palmar cutaneous branches of the median and the ulnar nerves in the palmar region were classified as Type A (34%), Type B (13%), Type C (13%), Type D (none), Type E (40%) according to forms of palmar cutaneous innervation originating from the ulnar and median nerves. Injury to the palmar cutaneous branch of the median nerve (PCBMN) is the most common complication of the carpal tunnel surgery. Various techniques were described to decrease post-operative morbidity. Based on these anatomic findings mini incision between the superficial palmar arch and the most distal part of the PCBMN in the palmar region is the safe-zone for carpal tunnel surgery.